The present invention relates generally to fuel injection pumps of the type having a rotary charge pump with one or more reciprocating pumping plungers for supplying sequential measured charges of fuel under high pressure to an associated internal combustion engine and relates more particularly to an improved control device for controlling the stroke of the pumping plungers.
In a fuel injection pump of the type having a rotary charge pump with reciprocating pumping plungers, it may be desirable to control the fuel charge measure supplied by the pump by limiting the outward or intake stroke of the plungers. U.S. Pat. No. 4,225,291 of G. W. Bouwkamp et al entitled "Fuel Injection Pump and Plunger Control Means Therefor" discloses such a device for limiting the stroke of the plungers.
In accordance with the present invention, several embodiments of a stroke control mechanism are provided which employ a new and improved plunger stroke limit device for variably limiting the outward stroke of the plungers. The stroke limit device is compact and useful with conventional rotary distributor type fuel injection pumps without substantial pump modification, has notable utility with conventional rotary charge pumps of the type having one or more pairs of diametrically opposed pumping plungers and is operative to limit the outward stroke of the charge pump plungers with a high degree of repeatability and parts reliability over a long service free life.
Further, in accordance with the present invention, the stroke limit device is useful in limiting the charge pump plunger stroke to a preestablished fixed limit or to each of two different predetermined stroke limits related to certain engine operating conditions or to an infinitely variable limit etablished in accordance with certain preselected engine operating conditions. Such engine operating conditions include throttle lever position, engine speed, engine altitude or inlet manifold pressure in turbocharged engine applications and engine starting.
A principal object of the present invention is to provide in a fuel injection pump of the type having a rotary charge pump with one or more pairs of diametrically opposed pumping plungers, a new and improved stroke limit device for limiting the outward stroke or displacement of the pumping plungers. In accordance with the present invention, the stroke limit device is compact, is useful with existing rotary distributor type fuel injection pumps without substantial pump modification, can be economically manufactured and provides accurate plunger stroke limit control for repeatable delivery of high pressure fuel charges of the same quantity or measure.
Another object of the present invention is to provide a new and improved stroke control mechanism which will adjust the stroke limit of the plungers in accordance with the throttle lever position. Included in this object is the provision of a pumping plunger stroke control mechanism which automatically compensates for changes in engine altitude or boost pressure in tubocharged engine applications and/or changes in engine speed.
Still another object of the present invention is to provide in a rotary distributor type fuel injection pump, a new and improved pumping plunger stroke control mechanism which provides additional fuel for starting.
A further object of the present invention is to provide a new and improved stroke control mechanism of the type described which is manually adjustable and which can be accurately and precisely set in a simple manner.
Another object of the present invention is to provide a new and improved stroke control mechanism of the type described which is automatically operable to shift the stroke limit of the pumping plungers between first and second preestablished limit settings.
Another object of the present invention is to provide in a rotary distributor type fuel injection pump, a new and improved stroke limit device of the type described which can be controlled in various ways to limit the size of the high pressure fuel charge delivered by the pump, for example by mechanical, electrical hydraulic and/or vacuum operated means of the fuel injection pump or the associated engine.
Other objects will be in part obvious and in part pointed out more in detail hereinafter.